<?php

/**
 * PHPTAL templating engine
 *
 * PHP Version 5
 *
 * @category HTML
 * @package  PHPTAL
 * @author   Laurent Bedubourg <lbedubourg@motion-twin.com>
 * @author   Kornel Lesiński <kornel@aardvarkmedia.co.uk>
 * @license  http://www.gnu.org/licenses/lgpl.html GNU Lesser General Public License
 * @version  SVN: $Id$
 * @link     http://phptal.org/
 */

/**
 * TAL Specifications 1.4
 *
 *      argument ::= expression
 *
 * Example:
 *
 *      <p tal:condition="here/copyright"
 *         tal:content="here/copyright">(c) 2000</p>
 *
 *
 *
 *
 * @package PHPTAL
 * @subpackage Php.attribute.tal
 * @author Laurent Bedubourg <lbedubourg@motion-twin.com>
 */
class PHPTAL_Php_Attribute_TAL_Condition extends PHPTAL_Php_Attribute implements PHPTAL_Php_TalesChainReader {

  private $expressions = array();

  public function before(PHPTAL_Php_CodeWriter $codewriter) {
    $code = $codewriter->evaluateExpression($this->expression);

    // If it's a chained expression build a new code path
    if (is_array($code)) {
      $this->expressions = array();
      $executor = new PHPTAL_Php_TalesChainExecutor($codewriter, $code, $this);
      return;
    }

    // Force a falsy condition if the nothing keyword is active
    if ($code == PHPTAL_Php_TalesInternal::NOTHING_KEYWORD) {
      $code = 'false';
    }

    $codewriter->doIf('phptal_true(' . $code . ')');
  }

  public function after(PHPTAL_Php_CodeWriter $codewriter) {
    $codewriter->doEnd('if');
  }

  public function talesChainPart(PHPTAL_Php_TalesChainExecutor $executor, $exp, $islast) {
    // check if the expression is empty
    if ($exp !== 'false') {
      $this->expressions[] = '!phptal_isempty(' . $exp . ')';
    }

    if ($islast) {
      // for the last one in the chain build a ORed condition
      $executor->getCodeWriter()->doIf(implode(' || ', $this->expressions));
      // The executor will always end an if so we output a dummy if
      $executor->doIf('false');
    }
  }

  public function talesChainNothingKeyword(PHPTAL_Php_TalesChainExecutor $executor) {
    // end the chain
    $this->talesChainPart($executor, 'false', true);
    $executor->breakChain();
  }

  public function talesChainDefaultKeyword(PHPTAL_Php_TalesChainExecutor $executor) {
    throw new PHPTAL_ParserException('\'default\' keyword not allowed on conditional expressions', $this->phpelement->getSourceFile(), $this->phpelement->getSourceLine());
  }

}
